Instrument and method for testing fluid characteristics

ABSTRACT

An instrument for testing fluid characteristics has a vial and a housing. The vial defines a chamber for receiving a sample of the fluid and has a cap for sealing the fluid therein. The housing defines a recess for receiving the vial. Multiple light emitting diodes and photovoltaic detectors are arranged on multiple meridional planes within the housing. The meridional planes each intersect approximately at a central axis of the chamber when the vial is placed within the recess. Modulation of the light emitting diodes and tuned processing electronics allow for simultaneous evaluation of sample characteristics such as spectral transmittance, turbidity and fluorescence. The user selects particular tests via a keypad and a display indicates the results of the chosen analysis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to instruments for measuring thecharacteristics of fluids, and more particularly, to an improvedinstrument and method for testing the color, turbidity and/orfluorescence of fluids such as water mixed with a reactant.

2. Background of the Related Art

Water quality monitoring at all levels of production and usage israpidly becoming a global necessity as sources of fresh potable waterbecome taxed by increasing populations. Even low levels of foreignmatter or contaminants can pose significant health and safety risks whenundetected. As a result, fast and accurate water testing results arerequired of an ever-expanding source of test samples. Consequently,there is a growing need for rugged portable instruments and methods formonitoring water quality as the treatment and usage of water expands.

Typically, the testing of water quality has involved the addition of aspecified reagent to a fluid sample. Conventionally, a reactant of knownconcentration is mixed with a water sample which contains a reactant ofan unknown concentration. Alternatively, the known reactant iscontinually added until a sample property change indicates the endpointof the reaction. In either case, the reagent reacts with the contaminantto create a reaction proportionate to the concentration of thecontaminant. Often, a color indicator is included so that a color changeoccurs, or the color change is inherent to the chemical reaction. Thus,subsequent to the addition of the reagent, visual inspection against aprinted color chart can determine the absence or level of an associatedcontaminant. Such purely visual comparisons are inherently subjective,and therefore unreliable for sensitive measurements. Generally, askilled technician is required to determine the degree of the reactionand interpret the results. Alternatively, a colorimeter or photometercan consistently measure the degree of reaction (e.g., the depth ofcolor or the spectral transmission) and, hence, the concentration of thecontaminant. However, traditional calorimeters and photometers are notpractical for field use and provide only color related data.

When the reaction product is a fine-particle precipitate, the sample canbe measured by optical turbidimetric methods, i.e. scattering. A highconcentration of precipitate as a result of a high concentration of thecontaminant creates increased scattering. Therefore, the level ofturbidity corresponds to the level of contaminant concentration.Alternatively, the presence or absence of a level of turbidity from asource in a natural fluid sample may be a critical indicator of thequality of such a fluid sample.

An additional technique is to add a reagent including a fluorescentmarker. The reaction with the contaminant may either enable or quenchthe fluorescent moiety. For example, the marker rhodamine will fluorescein the red when excited by blue light. Thus, transmitting blue lightthrough the sample will generate a red fluorescence proportionate to thelevel of contaminant. Accordingly, determining the change in the levelof fluorescence will indicate the concentration of the contaminant.Additionally, if the blue exciting light is repetitively pulsed and thefluorescence intensity is measured at a particular time after eachpulse, the time-decay rate of the fluorescence can provide furtherinformation on the chemical nature of the contaminant.

In view of the above, several systems have been developed to ascertainthe color, turbidity or fluorescence of a liquid sample. A traditionalcolorimeter includes a broadband light source. Filters are moved in andout of the optical path to provide different wavelengths. The filtersmay be moved manually or by motors. A lightpipe or lens system maycollect and direct the light to a point on the object to be tested. Atsuch points, the light reflects off opaque objects and passes throughtranslucent objects to receivers. The receivers, usually photodiodes,convert the light signal into an electrical signal for processing. Toprevent erroneous readings, the receiver must be isolated from ambientlight. To control the environment, the conventional calorimeter isusually utilized exclusively in a laboratory.

For example, U.S. Pat. No. 5,137,364 to McCarthy discloses an opticalspectral analysis device having light emitting diodes (hereinafter“LEDs”) and receivers mounted on the same substrate. Thus, onlyreflected light is analyzed. U.S. Pat. No. 5,229,841 to Taranowski etal. shows using a plurality of different colored LEDs which are runaccording to timing pulses. In synchronism with the LED timing pulses,the outputs of the photodiodes are sampled, and thus each output isindicative of an individual colored LED's signal. U.S. Pat. No.6,094,272 to Okamoto discloses receiving a sum total of reflected lightand comparing the summed value to a value associated with a referencetarget. The resulting comparison value is displayed in numerical form toindicate a match degree between the tested item and the reference item.U.S. Pat. No. 6,157,454 to Wagner et al. discloses a miniaturecalorimeter. The miniature colorimeter includes a body having a lightpipe for transmitting reflected light to a light sensor, three differentprimary colored light sources, a display panel and a measure button. Inoperation, the miniature colorimeter generates three color data pointsrepresenting the reflectance of the target measured at the wavelengthsof the three primary colors. A microprocessor analyzes the three datapoints and displays the results in various commonly known formats.Further, several patents are directed specifically to water testingmethods and devices. U.S. Pat. No. 5,618,495 to Mount et al. automatesthe process of determining when the endpoint of the reagent reaction isreached with the use of a computer in communication with a colorimeterand other devices. U.S. Pat. No. 5,691,701 to Wohlstein et al. uses thevoltages generated by photosensors to produce a ratio which indicatesthe condition of engine oil. If the test fluid is outside a presetacceptable limit, an alarm indicating the same is triggered.

A multitude of patents are directed to particular aspects ofphotoelectrically sensing the color of an object. For example, U.S. Pat.No. 5,303,037 to Taranowski discloses a color sensor illumination sourcewhich generates a white light evenly composed of red light, green lightand blue light directed at the same angle. The importance of a balancedsource is to yield relatively balanced color output readings. U.S. Pat.No. 5,471,052 to Ryczek shows a secondary photosensitive element whichreceives the light directly from the light source. As a result, thesignal from the secondary photosensitive element is used to create aclosed loop feedback signal to regulate the light source power output.

Additional patents have recognized that certain materials displaydifferent colors depending upon the angle of observation. In particular,U.S. Pat. No. 5,592,294 to Ota et al. recognizes the need to accuratelydetermine the angle of observation in order to render reproducibleresults. To solve this problem, Ota et al. incorporated an angledetector which controls an adjustment mechanism in order to set thedesired angle of observation repeatably.

U.S. Pat. No. 5,083,868 to Anderson discloses the need for a portablecolorimeter. The colorimeter is enclosed in a housing for receiving asample. When a vial is placed in the sample compartment, a cap member ispositioned in grooves to prevent interference from external light. U.S.Pat. No. 5,872,361 to Paoli et al. discloses a portable turbidimeterhaving a non-imaging optical concentrator between a sample cell and anoptical detector. A cover is utilized to reduce the effect of ambientlight on the readings. U.S. Pat. No. 5,604,590 to Cooper et al.discloses a nephelometer instrument for measuring very high waterturbidities, such as 10,000 NTUs. The nephelometer instrument has onelight source and four detectors. The detectors receive back scatter,forward scatter, 90° scatter and transmitted light.

Still further, several patents are directed to devices for onlydetermining the light penetrability of liquids. U.S. Pat. No. 5,696,592to Kuan teaches immersing a light guide and a liquid-tight photosensorin a liquid to be measured. When a light source illuminates the lightguide, the photosensor generates a signal indicative of thepenetrability of light for the test liquid. U.S. Pat. No. 6,055,052 toLilienfeld is directed to a system for monitoring airborne particulates.Lilienfeld appreciates the need for a portable instrument which candetermine ambient air quality in real time at remote locations. Each ofthe U.S. patents described above are incorporated herein by reference.

Despite the teachings of the above-mentioned patents, there are variousproblems associated with the systems and methods of the prior art asknown in the field of water testing. Many systems require thetime-consuming process of acquiring a sample and sending the sample to alaboratory for analysis. Alternatively, on-site analysis is oftensubjected to inconsistent results due to human error. Further, devicesof the prior art, particularly those designed for portable field use,yield only limited results. In the past, providing a device that couldconsistently and accurately indicate contaminant levels was far lessthan economic regardless of the location. There is a need, therefore,for an improved water testing instrument and method which permitsefficient and accurate readings of at least one, and preferably aplurality of parameters for a variety of applications and operatingconditions.

SUMMARY OF THE INVENTION

The present invention is directed to a method and device for opticallymeasuring qualities of a substance in ambient light, wherein the deviceincludes a translucent wall defining a sample chamber and an axis. Thetranslucent wall contains the substance to be measured. A radiationsource, such as an LED or other light source, is mounted adjacent to thesample chamber and emits a modulated beam of radiation distinguishablefrom the ambient light because the radiation is modulated. After passagethrough the sample chamber, the radiation is received by a detectorangularly spaced about the axis of the sample chamber relative to theradiation source. The detector generates a modulated output signalindicative of the intensity of the radiation of the beam impingingthereon. A controller activates the radiation source and the detectorand processes the modulated output signal for show on a display.

The present invention is also directed to an instrument and method formeasuring characteristics of a substance, wherein the instrumentincludes a sample chamber for receiving therein a sample of thesubstance. A signal generator has a radiation source mounted adjacent tothe sample chamber. The radiation source emits a beam of radiationthrough the sample chamber onto a detector of the signal generatorangularly spaced about the axis of the sample chamber relative to theradiation source. The detector receives the beam of radiation afterpassage through the sample chamber and substance to be measured therein.Upon receiving the radiation, the detector generates an output signalindicative of the intensity of the radiation impinging thereon. A memorystores reference measurement data based upon a plurality of differentreference samples, wherein each reference sample has a differentconcentration of an impurity. A controller in communication with thememory is operative to receive a signal from the signal generator basedupon a sample within the sample chamber having an unknown concentrationof an impurity. The controller automatically compares the signal to thereference measurements to determine a concentration of the impurity inthe sample and generate an output signal indicative of theconcentration.

The present invention is also directed to a method and device foranalyzing color and scattering of an elongated sample, such as a watersample contained in a vial, wherein the elongated sample defines anaxis. The device includes a first channel defining a first meridionalplane having a first radiation source mounted adjacent to the sample.The first radiation source emits a first beam of radiation through thesample onto a first sensor angularly spaced about the axis of the samplerelative to the first radiation source. The first sensor generates afirst output signal indicative of the intensity of radiation impingingthereon. A second channel defines a second meridional plane and includesthereon a second radiation source mounted adjacent to the sample. Thesecond radiation source also emits a beam of radiation through thesample onto a second sensor angularly spaced about the axis of thesample relative to the second radiation source for generating a secondoutput signal. Electronics activate each of the channels and process thesignals generated thereby. Preferably, the channels are about 45° apartto allow for color, transmission and 45° turbidity measurements.

One advantage of the instrument and method of the present invention, isthat they employ light sources which are modulated, and therefore thesignals generated thereby can be isolated. As a result, the instrumentand method are capable of functioning in ambient light. Further,multivariate analysis can be conducted simultaneously to gather datafaster than with traditional mechanisms.

Still another advantage of the subject invention is the simplifiedarrangement of stationary components which perform a multitude ofmeasurements. As a result, the reliability is improved and productioncosts are reduced.

These and other unique features and advantages of the instrument andmethod disclosed herein will become more readily apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those having ordinary skill in the art to which the disclosedinstrument and method appertains will more readily understand how tomake and use the same, reference may be had to the drawings wherein:

FIG. 1 illustrates a perspective view of an instrument for measuringoptical transmission, turbidity and fluorescence of a fluid sampleconstructed in accordance with subject disclosure;

FIG. 2 a is a partial schematic, perspective view of the optics of aninstrument constructed in accordance with a preferred embodiment of thesubject disclosure, wherein only two of three envisioned meridionalplanes are shown for simplicity;

FIG. 2 b is a partial schematic, side view of one meridional planeshowing the principle rays of three LEDs of an instrument constructed inaccordance with a preferred embodiment of the subject disclosure;

FIG. 2 c is a partial schematic, top view of one meridional planeshowing the principle ray and outermost rays of one LED of an instrumentconstructed in accordance with a preferred embodiment of the subjectdisclosure;

FIG. 3 is a schematic view of the optics and electronics of aninstrument constructed in accordance with a preferred embodiment of thesubject disclosure;

FIG. 4 is a partial schematic, top view of the optics of an instrumentconstructed in accordance with a preferred embodiment of the subjectdisclosure;

FIG. 5 is a partial schematic, top view of the optics used for ascattering measurement in accordance with a preferred embodiment of thesubject disclosure;

FIG. 6 a illustrates a perspective view of another instrument formeasuring optical transmission, turbidity and fluorescence of a fluidsample flowing in a transparent conduit in accordance with the subjectdisclosure;

FIG. 6 b is a cross-sectional view taken along line A-A of FIG. 6 a;

FIG. 7 a is a perspective view of a sample vial in accordance with anadditional preferred embodiment of the subject disclosure;

FIG. 7 b is a cross-sectional view of the base of the sample vial ofFIG. 7 a; and

FIG. 7 c is a bottom plan view of the base of the sample vial of FIG. 7a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention overcomes many of the prior art problemsassociated with water testing devices and methods. The advantages, andother features of the instrument and method disclosed herein, willbecome more readily apparent to those having ordinary skill in the artfrom the following detailed description of certain preferred embodimentstaken in conjunction with the drawings which set forth representativeembodiments of the present invention, and wherein like referencenumerals identify similar structural elements.

Referring to FIG. 1, a multi-axis photometric sensing instrument 100includes a housing 110 for protecting and aligning optical componentsmounted therein, a display 112 for indicating the results of a pluralityof measurements to a user, and a keypad 114 for receiving input from auser. The housing 110 defines a recess 116 for receiving therein anelongated sample vial 130 defining a chamber therein for receiving asample to be tested. As described further below, the recess 116 properlyaligns the sample vial 130 in the optical path for analysis. A port 118for communicating with a computer (not shown) and a socket 120 forcharging an internal power cell 121 (as seen in FIG. 3) are alsointegrated within the housing 110. Preferably, the port 118 is a serial,USB, IEEE1394 port or the like as is known to those of ordinary skill inthe pertinent art.

Preferably, the instrument 100 is watertight to increase its ruggedness.The optics and electronics, which in the currently preferred embodimentare LEDs and photovoltaic detectors (hereinafter “PVDs”), are fixedwithin the housing 110. It is envisioned that a multitude of optical andelectrical components may be used to fulfill the performancerequirements of the instrument. For example, without limitation,semiconductor lasers may replace the LEDs and photoFETs (photosensitivefield-effect transistors) or avalanche photodiodes may replace the PVDs.It is envisioned that any useful combination of analog and digitalsignal-processing electronic components may be used as the electricalcomponents. Reducing the number of moving parts provides for increasedreliability. As described in further detail below, the multi-axis,multi-source and multi-detector instrument 100 is selectively operatedby electrical switching to perform a plurality of tests.

Preferably, the sample vial 130 is a thin-walled, visually transparentor translucent, non-scattering scintillation tube in the form of awide-mouth, capped bottle. In a preferred embodiment, the sample vial130 is in the form of a clear glass or plastic cylinder having a heightof about 2 inches and a diameter of about 1 inch. As a result, thesample vial 130 will refract light passing therethrough. The mediumwithin the sample vial 130 will also interact with light passing throughthe sample vial. It is also envisioned that the sample vial 130 can besquare, rectangular, oblong or a multitude of other shapes as will beappreciated by those of ordinary skill in the pertinent art upon reviewof the teachings herein.

The sample vial 130 has a tabbed, screw-on plastic cap 132. The cap 132is preferably provided with a tab portion 133 for labeling, tighteningleverage when wet, and ease of handling. In one embodiment, the samplevial 130 is disposable to avoid cross-contamination from previous tests.Preferably, the sample vial 130 has a fill line 131 for indicating therequired amount of sample. As may be recognized by those of ordinaryskill in the pertinent art based on the teachings herein, thedimensions, materials of construction, and shape of the sample vial 130or other structures defining the sample chamber disclosed herein areonly exemplary, and may be changed as desired depending upon theparticular application of the instrument or otherwise as desired.

In operation, the sample vial 130 is filled with the test fluid andplaced within the recess 116 of the instrument 100. For example, thetest fluid may be a water sample taken from the output of a drinkingwater supply. In a preferred embodiment, the sample vial 130 acts bothas a sample holder and an optically refractive element necessary to theinstrument's functioning. In the illustrated embodiment, all otherhardware and software resides permanently in the remainder of thehousing 110, and specific instructions for any chemical/turbidimetrictests are entered through the keypad 114 of the housing 110. The userselects via the keypad 114 an appropriate test such as, withoutlimitation, color, turbidity and/or fluorescence, as described infurther detail below. The instrument 100 analyzes the test fluid and thedisplay 112 indicates the results of the test.

Now referring to FIG. 2 a, only meridional planes 154 b and 154 c areshown for simplicity. The sample vial 130 is located between multipleLEDs 150 and PVDs 152 when placed within the recess 116. In oneembodiment, nine LEDs 150 are arranged so that the principle rays 151emitting therefrom define three meridional planes 154 passing through acentral axis “z” of the sample vial 130 and converging at the centralpoints of their corresponding PVDs 152. The selection and arrangement ofthe LEDs 150 and PVDs 152 creates a plurality of defined meridionalplanes 154 a-c about the sample chamber's axis z. The LEDs 150 emit in aforward direction, but there is no need to further control the coneangle of the emission, other than the refractive focussing performed bythe sample vial 130. Preferably, the LEDs 150 are relatively smallview-angle LEDs. As shown, each of the LEDs 150 and PVDs 152 lie ondefined, fixed axes, and the meridional planes 154 a-c pass through axisz of the preferably cylindrical sample vial 130. Any angle effects areautomatically taken into account by zeroing with a pure water sample, asdescribed further below. In a currently preferred embodiment of thepresent invention, the three defined meridional planes 154 a-c (or“channels”) provide a total of nine different wavelength bandsdistributed over the near ultraviolet, visible and near infra-red(hereinafter “NIR”) range for liquid optical absorption. The resultingsensitivity and precision of photometric transmission measurementexceeds that of the human eye, and extends the usefulness of thechemical tests beyond that of classical visual color determination. Inone embodiment, the LEDs are selected with approximately 5 mm diametersand high brightness. The color of the light may be, without limitation,blue (430 nm peak emission wavelength), green (565 nm), red (660 nm),near IR (880 or 940 nm) and white. Preferably, the white LED is partnumber CMD333UWC available from Chicago Miniature Lamp. It is envisionedthat other selections of LEDs, PVDs, and other light sources anddetectors, including the wavelengths and positions of such light sourcesand detectors, would be obvious to one skilled in the art upon review ofthe subject disclosure.

Preferably, each LED's emission cone, the refractive power of the samplevial 130, and the width of each PVD 152, are selected in combination tocapture the full cone of light within the corresponding PVD. Thecircular cone of light emitted by each LED 150 is distorted into anoblong shape by passing through the sample vial 130. Hence, therectangular shapes of the PVDs are needed to catch all of the light. Ina preferred embodiment, each LED 150 is a high-brightness T-1 ¾ LEDlocated approximately 5 mm from the sample vial 130. Each LED emits intoa forward cone which preferably has a view-angle of less than about 30°,with emission roughly uniformly distributed within this cone of light.Each PVD 152 has an approximately 20×40 mm rectangular active area. Asuitable PVD is available from Radio Shack under part number #276-124A.Each PVD is placed approximately 19 mm from the sample vial 130 tocollect the forward cone of light emitted by the corresponding LEDs. Inanother embodiment, a PVD of approximately 20×20 mm may be used with asmall cylindrical lens (axis horizontal, not shown) placed in front ofeach LED 150 in the 5 mm space between the LED and the sample vial 130.The cylindrical lens condenses the vertical beam spread to fit on a 20mm high PVD or other sensor. The PVDs 152 are used in the photovoltaicmode to assure linearity of response to input signals, no dark current,and minimal sensitivity to the operating temperature of the instrument100. As may be recognized by those of ordinary skill in the pertinentart based upon the teachings herein, the dimensions and angles hereinare only exemplary and may be changed as desired or otherwise required.

Preferably, the optical system is simple to construct, and requires norigid tolerancing, as shown. To facilitate lightweight construction andautomatic alignment of the LEDs 150 in each meridional plane 154, apiece of metal or plastic (not shown) may be machined or molded tosecure the LEDs in place. In another embodiment, clear glass or liketransparent or translucent covers (not shown) are epoxied or otherwisesecured over the LEDs 150 and/or PVDs 152 to prevent water and dirtbuildup. In still another embodiment, a Wratten blue-pass filter (notshown) is cemented over the blue-emitting LEDs in one of the meridionalplanes to not only aid cleanliness, but to increase the signal-to-noiseratio during measurements. As described further herein, the instrument100 includes a microcontroller 174 (as best seen in FIG. 3) programmedin a manner known to those of ordinary skill in the pertinent art tocontrol the various switching regimes. Consequently, the only movingpart in the instrument 100 is preferably the hand-inserted sample vial130.

In another embodiment, four PVDs 152 can be arranged in an octagonalarrangement (not shown). In the octagonal arrangement, four LED channelsand four PVDs 152 allow twelve different LEDs 150 to be usedsimultaneously for photometric, transmission and turbidimetric orcolorimetric purposes. It is envisioned that small interference filters(not shown) in front of some of the LEDs can be used to sharpen thespectroscopy, if desired. Preferably, each of the four PVDs 152 isapproximately 20×40 mm; however, as may be recognized by those ofordinary skill in the pertinent art based upon the teachings herein,these dimensions are only exemplary and may be changed as desired orotherwise as required.

Referring now to FIGS. 2 b and 2 c, only one meridional plane 154 of thesensor is shown for simplicity. As shown, the meridional plane 154 liesin the plane defined by the axes x and z of a rectangular coordinatesystem. It will be appreciated by those skilled in the art that themeridional plane 154 shown represents the configuration of any ofmeridional planes 154 a-c and that axis z may be in any spatialdirection. For the preferred embodiment's capped sample vial 130, themost sensible direction to define axis z is approximately verticallyupwards. For other embodiments, such as the sample vial or chamberdefined by a quartz pipe or other transparent or translucent conduit forreceiving flowing fluids therethrough and described further below, thereare no practical restrictions on the length and orientation of axis z.In another embodiment shown in FIG. 2 c, a plain-glass beam-splitter 157(shown in broken lines) and small reference photocell 159, arepositioned so as to provide continuous monitoring of LED output powerand feedback to correct for LED variations, if such referencing isneeded or desired.

As shown in FIG. 2 b, the LEDs 150 are located at a distance “s1” in thex axis from the left glass wall of the sample vial 130 in the drawing,and are spaced some minimal distance “h1” in the z axis from each other.The principal ray 151 of each LED in the meridional plane 154 intersectsthe central portion of the respective PVD 152 along the z axis. The PVDs152 are oriented approximately perpendicular to the central axis of themeridional plane 154, and are spaced a distance “s3” in the x axis fromthe sample vial 130 in the drawing. As shown in FIGS. 2 b and 2 c, theexemplary PVD 152 defines a height “H” and width “W” and receives lightfrom any or all of the respective meridional plane's LEDs, sequentiallyor simultaneously. If two or more of the LEDs are “on” simultaneously,each source is preferably frequency modulated, or otherwise modulated asdesired (e.g., by phase or amplitude modulation) so that software of themicrocontroller 174 can analyze each PVD's output signal and separatethe components arising from each LED's emission, as described furtherbelow. For example, in a currently preferred embodiment, the frequencyof each LED or other light source is modulated approximately as follows:f1=1613 Hz, f2=1099 Hz, and f3=676 Hz.

With reference to FIG. 2 b, the height H of the exemplary PVD 152 isdetermined by the vertical beam spreads of the cones emitted by thecorresponding LEDs 150, as modified by refraction in the meridionalplane 154 by the water or other liquid-filled sample vial 130. As shownin FIG. 2 c, the width W of the exemplary PVD 152 is determined by therefraction in the x-y plane of the extreme rays 153 emitted in the LED'sforward cone of half-angle η (i.e., half the conventional view-angle ofthe LED 150).

Preferably, three meridional planes 154 are spaced octagonally (i.e.,about 45° apart) around the central axis z of the preferably cylindricalsample vial 130. For simplicity, FIG. 2 a shows only two meridionalplanes 154 b and 154 c. Preferably, each of the meridional planes 154contains a plurality of LEDs 150 of different peak wavelengths, and asingle PVD 152. Thus, the instrument 100 of the preferred embodiment hasnine distinct waveband LEDs 150 and three independent broad-area PVDs152. As may be recognized by those of ordinary skill in the pertinentart based upon the teachings herein, depending on the measurementapplication, a greater or lesser number of meridional planes may beused, with a greater or lesser number of LEDs per meridional plane. Ifthe sample vial 130 is scaled up or down in diameter, then the opticaldesign will require s1 and s3 to vary (see FIG. 2 b), particularly sothat the PVD widths W (see FIG. 2 c) can be constrained to avoid thephysical overlapping of adjacent PVDs. In theoretical design and testsof the preferred embodiment, where the diameter s2 of the sample vial130 is about 25.4 mm, it has been found that for LEDs with view angleswhere 2η is less than or equal to about 24°, the useful dimensions inthe system are an “s1” of greater than about 5 mm but less than about 10mm, an “s3” of about 15 mm, and “W”×“H” equal to about 20×40 mm, whichare commonly available PVD dimensions. However, as may be recognized bythose of ordinary skill in the pertinent art based upon the teachingsherein, any of these dimensions and angles may be changed as desired orotherwise required.

Referring now to FIG. 3, when three meridional planes 154 a-c are usedin an octagonal configuration, it is useful to use only a triplet oforange, red and NIR LEDs 150 a in meridional plane 154 a, and only deepgreen and blue LEDs 150 c in meridional plane 154 c, so thatcomplementary long-pass and short-pass filters 178 and 176,respectively, are deployed in front of PVDs 152 a and 152 c,respectively, to reduce stray light in the instrument. Wratten gelatinfilters #25 and #47 have been found to be satisfactory in this regardfor the long and short filters, respectively. In the preferredembodiment, a doublet of yellow and green LEDs 150 b are used inmeridional plane 154 b.

In the embodiment of FIG. 3, a plurality of oscillators 170 a-c areswitchably connected to the seven LEDs 150 a-c, respectively. Uponactivation, a power cell 121 provides current to the oscillators.Preferably, each oscillator 170 generates a square wave of a uniquefrequency. Switching circuitry within a switching circuitry area 172receives the oscillator outputs and determines which LEDs areilluminated depending upon the specific analysis requested by the user,as will be described in more detail below. For exemplary purposes, asimplified switching scheme is illustrated within the switchingcircuitry area 172. It will be appreciated by those skilled in theelectronic switching art that the specific switching circuitry is notlimited to the simplified version illustrated, and that a multitude ofcombinations beyond that shown are contemplated hereby. The use ofelectronic switching as opposed to manual allows for rapid sequentialreadings which are only limited by the settling times of the associatedpreamplifiers 180 a-c, amplifiers 188 a-c and display 112. Amicrocontroller 174 provides the instructions to actuate the oscillatorsand associated switching circuitry. The microcontroller 174 has amicroprocessor 184 and memory 186 operatively connected thereto. It willbe appreciated by those skilled in the pertinent art that themicroprocessor 174 can directly generate the modulating frequencies forthe LEDs 150. Thus, the analog oscillators 170 may be unnecessary.

Still referring to FIG. 3, the seven LEDs 150 are of various colors.Preferably, the seven LEDs consist of light blue (B+) and dark blue (B−)LEDs 150 c within the meridional plane 154 c, yellow (Y) and green (G)LEDs 150 b within the meridional plane 154 b, and red (R), orange (O)and infrared (IR) LEDs 150 a within the meridional plane 154 a. Thelight emitting from the LEDs 150 passes through the sample vial 130.Within the sample vial 130, the light is refracted and scattered, ifturbidity exists, as described above with respect to FIGS. 2 a, 2 b and2 c. It is envisioned that two of the PVDs 152 will receive filteredlight. In a preferred embodiment, and as described above, PVD 152 a inmeridional plane 154 c has a red light blocking filter 176 associatedtherewith (e.g., Written #47), and PVD 152 a has a blue-green blockingfilter 178 associated therewith (e.g., Written #25). The use of opticalfilters aids in reliably separating the average fluorescence emissionintensity from scattered intensities. In the case of sensingfluorescence by pulsed excitation or time-delay gated methods, thephysical filters may be omitted.

When the PVDs 152 a-c convert the light into an electrical signal, theresulting electrical signals are modulated at the same frequencies asthat of the oscillators 170 a-c which supplied power to thecorresponding LEDs 150 a-c. The modulation not only allows sorting outthe signal from ambient light, which automatically eliminates sun androom lighting from having any effect on the instrument's performance,but also sorts out the signal as opposed to that generated by the otherLEDs if more than one LED is activated at any one time.

In a preferred embodiment, one of a plurality of preamplifiers 180 a-cboosts each signal generated by the corresponding PVDs 152 a-c. Themicrocontroller 174 determines the timing and duration of the activationof the preamplifiers 180 a-c by controlling additional switchingcircuitry within switching area 182 of a type known to those of ordinaryskill in the pertinent art. The boosted signals are variably routed byswitching circuitry 182 to a summing amplifier 184 according to thespecific analysis requested by the user, as will be described in moredetail below. Whichever preamplifiers 180 a-c are turned on, thecorresponding signal is sent to the summing amplifier 184. The pluralityof amplifiers 188 a-c are each tuned to a respective frequency ofmodulation to receive the boosted signals. The tuned amplifiers 188 a-cfurther boost the portions of the signals which are at the modulationfrequencies of the oscillators 170 a-c while rejecting or dampeningother frequencies. The outputs of the tuned amplifiers 188 a-c areprocessed by the microcontroller 174 and input to the display 112 forreview by the user. It is envisioned that the display 112 may be a LCDscreen, a printout, a digital meter, an analog needle gauge, or the likeas is known to those skilled in the art. The outputs of the tunedamplifiers 188 a-c also are stored in memory 186 as data. Softwarestored in the memory 186 provides instructions to the microprocessor 184to process the data of the particular test. Preferably, the data and/orresults are transmitted to an external computer (not shown) via the port118 for further analysis and long-term storage on a periodic basis. Inanother embodiment, the above sequence of preamplification, switching,summing and frequency-selective tuned amplification, relevant to theanalog representation of the instrument 100 can be replaced at any pointafter preamplification by a number of alternative digital methods ofsignal processing. For example, a switched capacitor filter, a digitalsoftware filter, synchronous demodulation and the like can be used toextract the signal directly from the PVD preamplifier outputs 180 a-c.The flexibility of microprocessor-controlled switching allowsmeasurements of any PVD output caused by any LED's modulated emission.

Referring now to FIG. 4, for simplicity, an overhead plan view of theoptical components in another preferred embodiment of the instrument 100includes three LEDs 150 a-c and three PVDs 152 a-c in six of the eightpositions allowed by an octagonal configuration. The PVDs 152 measuresample transmission in their respective meridional planes 154 a-c and,by suitable switching, the light scattered by a turbid liquid, i.e.,turbidity. An optional fourth PVD 152 d is positioned approximately 22.5degrees from PVD 152 a. The fourth PVD 152 d allows for additionalcollection of light which has been scattered within the sample vial 130.In this embodiment, the protective color filters in meridional planes154 a and 154 c have been dispensed with so as to allow scatteringmeasurements from any of the plural LEDs in any meridional plane 154 a-cto any of the four PVDs 150 a-d. It is envisioned that a multitude ofconfigurations would accomplish the measurements contemplated herein, aswould be readily recognized by one skilled in the art upon review of thesubject disclosure.

To increase the accuracy of the instrument 100 whenpost-preamplification and modulated signal measurements are carried outby any desired combination of digitized or analog components, straylight is preferably minimized. Undesirable stray light originates fromweak radiation directed from an LED 150 outside the view-angle cone,surface reflection upon entering the sample vial 130, optical scatteringby bubbles and/or particulates in the liquid or fluid in the sample vial130, internal reflection upon exiting the sample vial 130, and/orreflection and scattering at the PVD 152 surface. One advantage of usingLEDs in three meridional planes, as shown in the arrangement of FIG. 3,is the reduction of stray light effects. The stray light can be furtherreduced by the addition of black absorbers 190 a and 190 b, as shown bybroken lines in FIG. 4, within the empty spaces of the unused meridionalplane between the LED and PVD sides of the optical system. As shown, theblack absorbers between adjacent LEDs can extend inwards substantiallyadjacent to the sample vial 130.

To further increase the accuracy of the instrument 100, periodiccalibration is appropriate. For periodic calibration, the sample vial130 is sealed and contains pure bubble-free water (“the zeroingbottle”). The zeroing bottle is inserted in the instrument 100 to checkand reset in memory 186 the instrument's clean-water transmission andany direct or scattered stray light levels. Resetting the storedbase-line levels at the time and location of use corrects for instrumentambient operating temperature fluctuations, component aging, and willsignal the user if some mis-function or major departure from factory-setlevels has occurred. The clean-water scattered stray light values storedin memory 186 are mathematically subtracted from sample turbiditymeasurements to determine actual turbidity. Similarly, the clean-watertransmission signals stored in the memory 186 for each LED are used asthe divisors in computing the transmissivity of the test fluid in thesample vial 130.

Operation

Generally, in operation, the instrument 100 is loaded with standardcalibration data. In another embodiment, the instrument 100 performs aseries of laboratory readings to generate unique calibration data forstorage. It is also envisioned that the instrument may not requirestored calibration data, and that field generated reference data will besufficient to perform the desired analysis. During use of the instrument100, a user inserts a sample vial 130 into recess 116. As appropriatefor a particular analysis, one sample vial 130 may contain clearbubble-free water for zeroing during periodic calibration and othersample vials 130 may contain an unmodified field sample, or a fieldsample with a reagent added thereto, wherein several readings based upondifferent substances may be required to complete a particular analysis.The user selects the desired analysis and initiates the process viakeypad 114. The microcontroller 174 activates the required LEDs 150 a-cand PVDs 152 a-c, and provides instruction to the user via display 112as required for the selected analysis. If necessary, the user manuallyinserts the appropriately filled sample vial 130 at the appropriate timeas prompted by the display 112. The electronics, including withoutlimitation the amplifiers and microcontroller, process the signalsgenerated by the readings, display the results to the user on display112, and store the results in memory 186 for subsequent download to anexternal apparatus via port 118. If the instrument 100 becomes low onpower, the user may recharge the internal battery via receptacle 120 aswould be known to those skilled in the pertinent art.

Color Change Measurements

Referring again to FIGS. 3 and 4, optical absorption of light passingstraight-through the sample vial 130 provides color-change data. It isrecognized that color is a psychophysical perception, and therefore anopto-electronic device cannot obtain such a measurement. However, forsimplicity, the term color is used to refer to the multi-wavelengthphotometry disclosed herein. Thus, there is no true concern for thevisual color of the fluid target, just the photometric transmission atparticular wavelengths.

To obtain a baseline for the instrument 100, precision spectroscopy isconducted in a laboratory. The results are stored in the memory 186 tobe used in combination with digitized data from the output of the tunedamplifiers 180 a-c (see FIG. 3). Preferably, if a reagent is required toeffect the color change, the instrument 100 is carried with a kitcontaining the various necessary chemicals and reagents.

If a reagent needs to be added to the sample in order to effect a colorchange, it is envisioned that two samples will be taken. One of thesamples will provide a baseline “natural color” reference and the secondsample will have the reagent added thereto. Each sample should bemeasured following substantially the exact same process, but for theaddition of the reagent. It is also envisioned that a reagent may needto be added to create a fluorescent effect.

For many color measurements, only red, green and blue+LEDs 150 need tobe utilized. In one embodiment, the red, green and blue+LEDs are LEDs150 a-c, respectively, as shown in FIG. 4. The three LEDs are eachmodulated at a different frequency. As a result of the three beams oflight passing through the sample vial 130, red, blue+ and green readingsare output to the display 112 indicating a color reading for the sample.For less sophisticated color tests, the redundancy of three differentcolor channels may not be necessary. For example, a bluish sample mayonly require color analysis using the red channel. For moresophisticated color tests, any subset of up to twelve different colorLEDs, e.g., as in an octagonal configuration, operated simultaneously atdifferent modulation frequencies, or sequentially at a single modulationfrequency, may be used for a color analysis.

In another embodiment, the instrument 100 indicates the concentration ofa predetermined impurity. The concentration is based upon comparison ofdata from a field sample to data points stored in the memory 186. In thepreferred embodiment, the stored data is representative of a log-linearBeer's Law plot. A Beer's Law plot is made by measuring the transmittedlight signal (T) of solutions of varying concentration without varyingthe path length of the light or the wavelength, and dividing T by thetransmitted light signal of a pure water sample (T_(o)) with the samepath length and wavelength. A plot of the logarithm of the ratio againstconcentration is a Beer's Law plot. A linear Beer's Law plot indicatesthat the Beer-Lambert relationship holds for the solution at theparticular wavelength and the Beer's Law plot is used in determining theconcentration of unknown solutions. Symbolically, the Beer-Lambertrelationship is “T/T_(o)=10^(−A)”, in which case “A=εbc”, where A is theabsorption coefficient, ε is the molar absorbtivity, b is the pathlength, and c is the concentration of the compound in the solution.Preferably, the stored data points are generated under controlledconditions in a laboratory by measuring several samples of knownimpurity concentrations with the instrument 100. Upon acquisition of anabsorption or transmission reading from a field sample, the stored datais compared to the reading from the field sample to find thecorresponding impurity concentration in a manner known to those ofordinary skill in the pertinent art based upon review of the teachingsdisclosed herein. For example, the microcontroller 174 selects first andsecond data points above and below, respectively, the reading from thefield sample. Based upon the field sample reading, and the first andsecond data points, the microcontroller mathematically interpolates toarrive at an impurity level for the field sample.

It also will be appreciated by those skilled in the art that if thenatural color of the field sample has undesirable turbidity orcoloration, a natural color sample may be used as a zeroing referencepoint to further enhance the accuracy of the resulting concentrationanalysis. In another embodiment, to further increase the reliability ofthe concentration analysis, multiple colors may be utilized withcorresponding sets of stored data points. Thus, the results for analysiswith one color would verify the results of another color.

Scattering and Turbidity Measurements

FIG. 5 depicts a currently preferred configuration of the components forconducting turbidity measurements, and is seen to contain a portion ofthe same components in the same relative positions as shown in FIGS. 3and 4. The switching circuitry changes according to microprocessorcontrol to accomplish the selected turbidity measurement in a mannerknown to those of ordinary skill in the pertinent art based upon theteachings herein. Turbidity data is preferably based upon 45° lightscattering at about 45° or thereabouts.

In one embodiment, blue turbidity is measured by activating theblue+beam's LED 150 c. It will be appreciated by those skilled in theart that such an instrument 100 may contain additional components whichare not shown for simplicity. For example, such components would processthe signals and facilitate performing additional measurements asdescribed hereinbelow. As light from the blue+LED 150 c passes throughthe sample vial 130, a portion of the light is scattered and impingesupon PVD 152 b of the adjacent channel. PVD 152 b has no color filter soa signal modulated at the frequency of blue light is generated by thescattering. The amplifier 188 (see FIG. 3) is tuned to the blue lightfrequency. After first measuring the sample transmission by amplifyingthe signal from PVD 152 a, the amplifier 188 is then switched to amplifythe signal of PVD 150 b only, and the strength of the signal isproportionate to the 45° turbidity. As a result, the instrument 100displays a value on the display 112 indicative of the turbidity of thesample.

Still referring to FIG. 5, NIR emission turbidity can also be measured.Preferably, LED 150 a is a modulated source providing NIR, PVD 152 a isthe transmission monitor, and unfiltered PVD 152 b is the sensor for NIRscattering approximately 45° off-axis. Since international practices inmonitoring water turbidity currently specify the use of 860 nm NIR lightin some instances, and long-wave blue light in others, the ability tomeasure both turbidities in the same instrument 100, with no movingparts, is easy for the user and avoids potential operator error. Instill another embodiment, as shown in FIG. 4, placement of a fourthand/or a fifth PVD (not shown) can receive 22.5° light from meridionalplanes 154 a and c, respectively, for a corresponding turbiditymeasurement.

For measurements, and particularly for turbidity, zeroing technique andcleanliness are important because air bubbles, lint, smudges and thelike may cause undue scattering which may in turn affect the results. Ina preferred embodiment, a technician follows the method below in orderto efficiently and accurately conduct a turbidity measurement:

-   -   1. Select turbidity from a list of measurements shown on the        display 112 via the keypad 114.    -   2. Perform a periodic zeroing to acquire and store clean-water        transmissions and stray light signals for all components to be        used in the specific turbidity test. As necessary, cleaning and        wiping of sample vial 130 is performed. Additionally, inspect        for potential sources of undesirable turbidity such as, without        limitation, minute air bubbles clinging to the inner glass        and/or water interface of the chamber.    -   3. Fill a sample vial 130 with a sample of the water to be        measured. Inspect the filled sample vial 130 for potential        sources of undesirable turbidity similar to the previous step.    -   4. Insert the sample vial 130 into the instrument 100.    -   5. Initiate the measurement by depressing an appropriate button        on the keypad 114 and view the desired result on the display        112.

If addition of a reagent is required to create the scattering particleswithin the sample, additional steps may be required. An additionalsample vial 130 should be filled with a sample and sealed. Even thoughno reagent is added, the additional sample vial 130 should be treated,i.e., shaken, substantially exactly as the sample vial 130 with thereagent, and a baseline reading taken to account for any naturalturbidity present in the original sample. Thus, by using such areference point with a similar shaking history, the effects of settlingand preparation within the sample are mathematically subtracted by themicrocontroller 174, in a manner known to those of ordinary skill in thepertinent art, to yield a true turbidity result.

Fluorescence Measurements

Still referring to FIG. 5, fluorescence can be measured using direct andapproximately 90° emission. In one embodiment, excitation occurs alongthe blue channel by LED 150 c. The meridional PVD 152 c indicates blueLED intensity when the sample vial 130 contains clear water, naturalliquid transmittance when the sample chamber contains a “natural color”water sample, and reacted liquid transmittance when the sample vial 130contains the natural water after chemical reaction with a fluorogenicagent. When a fluorescent reaction product emits in the red, the signalgenerated by PVD 152 c is solely that of the blue exciting lighttransmitted through the sample vial 130 because the red light is blockedby the filter 176 located in front of PVD 152 c. The red fluorescence isdetected by PVD 152 a at about 90° to the exciting blue light beambecause the red fluorescence passes through the filter 178 located infront of PVD 152 a. Preferably, during this measurement, all LEDs in theinstrument except the blue+LED 150 c are switched off to reduce thesignal-to-noise ratio. The red fluorescence signal arising from PVD 152a has the same modulation frequency as that of the exciting beam, andtherefore to still further reduce electronic noise, the signal fromdirect PVD 152 c is switched off when that from PVD 152 a is measured.It will be recognized by those of ordinary skill in the art that theinstrument 100 for fluorescence measurement is physically no differentfrom the embodiments discussed above for transmittance and turbiditymeasurements, and that only electrical switching changes controlled bythe software of the microprocessor 184 in a manner known to those ofordinary skill in the pertinent art are required.

In another embodiment, multiple blue LEDs on the meridional plane 154 cincrease excitation intensity, and in turn increase the generated signalstrength. To further increase the strength of the fluorescence signal,receiving PVD 152 a may be placed closer to the sample vial 130 toincrease the collected fluorescence signal. The fluorescence sensitivitycan be increased still further if the receiving PVD 152 a is anappropriately molded Winston cone and avalanche photodiode detector, aswould be appreciated by those of ordinary skill in the pertinent art.

Multivariate Measurements

Multivariate analysis is analyzing two or more different sets of datasimultaneously using matrix mathematics in a manner known to those ofordinary skill in the pertinent art to separate out the results. Forexample, turbidity and fluorescence measurements can be collectedsimultaneously with the instrument 100. Simultaneous transmission andscattering measurements can be taken with no cross-talk because the LEDs150 are modulated at different frequencies. Simultaneous transmissionmeasurements at multiple wavelengths can be made on a liquid sampleundergoing multiple, non-interacting chemical tests which produce knownoptical absorption changes at different wavelengths. Various algorithmsof a type known to those of ordinary skill in the pertinent art arecarried out by the microcontroller 174 to process such multivariatedata. Examples of multivariate analysis are given in “Applications andLimitations of Genetic Algorithms for the Optimization of MultivariateCalibration Techniques” by Matthew Mosley (Clemson University, 1998),which is incorporated herein by reference in its entirety.

A plurality of readings can also be conducted sequentially. Theintervals between readings are limited by the settling time of theamplifiers and the display 112. For example, photometric andfluorometric, or photometric and turbidimetric measurements can beconducted within seconds by multiple light beams directed along multiplemeridional planes 154 of the sample vial 130. While such sets ofsequential measurements require only conventional calculational means,the intentional redundancy of data supplied is advantageously treated bymultivariate methods known to those of ordinary skill in the pertinentart to greatly increase the user's confidence in, and awareness of, thestatistical accuracy of the instrument's output.

Alternative Embodiments

Referring to FIGS. 6 a and 6 b, the instrument 200 is adapted to takemeasurements of a fluid or other material passing through the samplechamber 230 in the form of a transparent or translucent conduit 232. Toachieve this, the instrument 200 contains multiple LEDs 250 and multiplePVDs 252 on multiple meridional planes (only one shown for simplicity).A microcontroller 274 is also housed within the instrument 200.Preferably, the LEDs 250 are secured on one side of the conduit 230 andthe PVDs 252 on the other side. For simplicity, only one set of LEDs 250and PVD 252 are shown in FIG. 6 a. The instrument 200 is halved along acenter line passing parallel to the sample chamber axis z′. Preferably,the two halves of the instrument 200 are secured together by a hinge 240and a closing latch 242. The transparent conduit 230 defines the samplechamber therein. In one embodiment, the outer diameter of the conduit230 is about 1 inch to allow a configuration of meridional planes 254 asdescribed above. Such an arrangement permits continuous transmission,turbidity and fluorescence measurements of a material flowing throughthe conduit 230. It is envisioned that this arrangement is applicable inindustrial photochemical and biochemical reactors, municipal water andsewerage plants, nuclear power plant fuel rod storage facilities, andthe like.

In monitoring flowing fluids, it may be advantageous to scale down theoptical sensing instrument 200 to accept sample pipe outer diameters of0.5 inches or less. Accordingly, in the scaled-down embodiment, the LEDsshould be 3 mm instead of 5 mm with small view angles of approximately20°. Alternatively, semiconductor lasers could be used as the radiationsource where appropriate in lieu of the LEDs 250, with PVDs 252 of evensmaller surface area than 20×20 mm as described above. Applicationsutilizing 0.5 inch diameter quartz pipe sample chambers includeeverything mentioned above, plus common relatively smaller tube pipingin chemical, pharmaceutical and food processing plants and the like. Asmay be recognized by those of ordinary skill in the pertinent art basedon the teachings herein, the optical components of the instrument 200may be scaled up or down to meet the requirements of any of numerousdifferent applications or uses that are currently or later become known.

Only minor design changes in the positioning of the PVDs 252 along theaxes of their meridional planes 254 are required to accommodatemonitoring of petrochemical fluids having refractive indices higher thanwater, e.g., in the 1.4-1.5 range. Transmission and particulateconcentration monitoring can also be carried out on low refractive indexfluids, such as flowing industrial and engine exhaust gases, andlow-temperature super-critical and critical fluids, such as condensedCO₂. In order to collect substantially all of the light energy, thesemeasurements require the use of large-area PVDs and very low view-angleLEDs, such as 10° light cones and/or semiconductor lasers, because noappreciable refractive light-beam shaping takes place in passage throughthe sample. Preferably, for high temperature and low temperature flowingfluids, the sample-containing tubes 230 are vacuum sealed insidesomewhat larger outer quartz tubes to thermally insulate the samplesfrom the optical sensing instrument 200. In such an arrangement, thePVDs 252 are preferably designed to fit closely around the outerinsulating tube.

Referring now to FIGS. 7 a through 7 c, another preferred embodimentmakes use of a sample chamber 300 with an integrated circuit 320. Thesample chamber 300 has a cap 332 and a plastic base 310. The base 310 issecured by a press fit, epoxy or other method known to those of ordinaryskill in the pertinent art. As shown in FIG. 7 b, the base 310 containsan embedded integrated circuit or printed circuit board 320 whichcarries electronic devices such as non-volatile, erasable, writablememory. The electronic devices store specific test softwareinstructions, test-specific calibration data, user interfaceconfiguration data and the like as may be desired. The printed circuitboard 320 of the sample vial 300 also contains an identifying numberwhich positively relates the sample vial 300 to prepackaged chemicals,such as reagents, that may be inside or supplied with the sample vial300. Upon insertion in the instrument 100, the instrument 100 recognizesthe sample chamber 300 by the identifying number, and receives thenecessary instructions to perform the appropriate measurements and toautomatically start the selected test. Thus, the user only needs to fillthe sample chamber within the sample vial 300 and insert the sample vial300 in the instrument 100. If desired, the sample chamber 300 may bereusable depending upon the chemical test or series of tests conductedtherewith.

Referring to FIG. 7 c, the sample vial 300 communicates with theinstrument 100 through the base 310, when placed in the recess 116 ofthe instrument 100. Preferably, the weight of the filled sample vial300, regardless of its rotational orientation in the recess 116, causescontacts in the base 310 to come into electrical contact withspring-loaded contact buttons embedded in the recess 116 of theinstrument 100. In one embodiment, an outer contact ring 312 mountedwithin the recess 116 of the instrument establishes the commonelectrical ground, and a central contact 316, also mounted on the baseof the recess 116 and electrically coupled to the microprocessor 184,communicates power and multiplexed electrical signals back and forth. Itis also envisioned that the base 310 and instrument 100 may beelectronically connected by a capacitive coupling, by low-power“RFID”-type technology, by magnetic coupling, by any ordinaryopto-electronic remote control, and the like.

It will be appreciated by those of ordinary skill in the pertinent artthat the components and dimensions described above are only exemplaryand can be changed as desired or required by new applications.Accordingly, the detailed description of preferred embodiments is to betaken in an illustrative, as opposed to a limiting sense. While theinvention has been described with respect to preferred embodiments,those skilled in the art will readily appreciate that various changesand/or modifications can be made to the invention without departing fromthe spirit or scope of the invention as defined by the appended claims.

1. A device for optically measuring qualities of a substance in ambientlight comprising: at least one translucent wall defining a samplechamber for receiving therein the substance to be measured and definingan axis; at least one first radiation source mounted adjacent to thesample chamber, wherein the first radiation source emits a modulatedbeam of radiation distinguishable from the ambient light based on saidmodulation; at least one first detector angularly spaced about the axisof the sample chamber relative to the first radiation source, whereinthe first detector receives the modulated beam of radiation afterpassage through the sample chamber and substance to be measured therein,and generates a modulated output signal indicative of the intensity ofthe radiation of the beam impinging thereon; a controller coupled to thefirst radiation source and the first detector for activating the sourceand processing the output signal; and a display coupled to thecontroller for displaying measurement readings based on the outputsignals.
 2. A device as recited in claim 1, further comprising a housingdefining a recess, and wherein the at least one translucent wall isformed by a vial defining the sample chamber therein, and the firstradiation source and first detector are mounted adjacent to the recess.3. A device as recited in claim 1, wherein the at least one translucentwall is approximately cylindrical.
 4. A device as recited in claim 1,further comprising at least one oscillator coupled to the at least onefirst radiation source for modulating the source.
 5. A device as recitedin claim 1, further comprising at least one amplifier coupled to thefirst detector for boosting the output signal and dampening otherfrequencies.
 6. A device as recited in claim 1, further comprising: atleast one second radiation source mounted adjacent to the sample chamberand angularly spaced about the axis of the chamber relative to the firstradiation source, wherein the at least one second radiation source emitsa second modulated beam of radiation distinguishable from the ambientlight and the modulated beam of the first radiation source based on saidmodulation.
 7. A device as recited in claim 6, further comprising: atleast one second detector angularly spaced about the axis of the samplechamber relative to the second radiation source, wherein the seconddetector receives the modulated beam of radiation from the secondradiation source after passage through the sample chamber and substanceto be measured therein, and generates a second modulated output signalindicative of the intensity of the radiation of the beam impingingthereon. 8 A device as recited in claim 7, further comprising an opticallong-pass filter positioned in front of the second detector forseparating a fluorescence emission intensity from scattered intensitiesof the at least one first radiation source and for reducing stray light.9. A device as recited in claim 1, further comprising a plurality offirst radiation sources, each first radiation source emitting aprinciple ray wherein the principle rays extend through the axis onto acentral region of the first detector.
 10. A device as recited in claim1, wherein the at least one first radiation source is a light emittingdiode.
 11. An instrument for measuring characteristics of a substancecomprising: (a) a sample chamber for receiving therein a sample of thesubstance and defining an axis; (b) a signal generator including atleast one radiation source mounted adjacent to the sample chamber foremitting a beam of radiation through the sample chamber, and at leastone detector angularly spaced about the axis of the sample chamberrelative to the radiation source, wherein the detector receives the beamof radiation after passage through the sample chamber and substance tobe measured therein, and generates an output signal indicative of theintensity of the radiation of the beam impinging thereon; (c) a memoryoperatively coupled to the signal generator for storing data including aplurality of reference measurements based upon a plurality of differentreference samples, wherein each reference sample has a differentconcentration of an impurity; and (d) a controller in communication withthe memory, wherein the controller is operative to: (i) receive a signalfrom the signal generator based upon a sample within the sample chamberhaving an unknown concentration of an impurity; (ii) automaticallycompare the signal to at least a portion of the reference measurementsto determine a concentration of the impurity in the sample; and (iii)generate an output signal indicative of the concentration.
 12. Aninstrument as recited in claim 11, further comprising a vial definingtherein the sample chamber and a recess for removably receiving thereinthe vial.
 13. An instrument as recited in claim 11, wherein the samplechamber is defined by a conduit allowing a field sample to flowtherethrough, the impurity is dissolved in the free-flowing substance,and the controller is further operative to monitor the concentration ofthe impurity.
 14. An instrument as recited in claim 11, furthercomprising a display for receiving the output signal and generating ahuman readable version of the output signal.
 15. An instrument asrecited in claim 11, wherein the signal generator is modulated at agiven frequency, and the signal is thereby modulated to distinguish thesignal from ambient light and other signals modulated at differentfrequencies.
 16. An instrument as recited in claim 11, furthercomprising at least two signal generators, each defining a separatechannel and meridional plane angularly spaced apart about the axisrelative to each other.
 17. An instrument as recited in claim 11,wherein the controller performs the comparison by selecting first andsecond data points within the plurality of reference measurements, thefirst and second data points are above and below the signal,respectively, and the controller mathematically interpolates the datapoints to arrive at the output signal.
 18. A device for analyzingradiant transmission and scattering of an elongated sample, wherein theelongated sample defines an axis, the device comprising: a first channeldefining a first meridional plane having the axis extending therethroughand including thereon at least one first radiation source mountedadjacent to the sample for emitting a first beam of radiation throughthe sample, and at least one first sensor angularly spaced about theaxis of the sample relative to the first radiation source for generatinga first output signal indicative of the intensity of radiation impingingthereon; a second channel defining a second meridional plane having theaxis extending therethrough and including thereon at least one secondradiation source mounted adjacent to the sample for emitting a secondbeam of radiation through the sample, and at least one second sensorangularly spaced about the axis of the sample relative to the secondradiation source for generating a second output signal indicative of theintensity of radiation impinging thereon; and electronics for activatingeach of the channels and processing signals generated thereby.
 19. Adevice as recited in claim 18, wherein the at least one first radiationsource includes a plurality of light emitting diodes axially spacedrelative to each other, and wherein each light emitting diode ispositioned so that a principle ray emitting therefrom substantiallypasses through the axis of the sample and onto the first sensor.
 20. Adevice as recited in claim 18, wherein the first and second radiationsources are selected from the group including green, red, yellow,orange, blue and near-infrared light emitting diodes.
 21. A device asrecited in claim 18, wherein the first and second channels are angularlyspaced approximately 45° apart.
 22. A device as recited in claim 18,further comprising a third channel defining a third meridional planeextending through the axis and including thereon at least one thirdradiation source mounted adjacent to the sample for emitting a thirdbeam of radiation through the sample, and at least one third sensorangularly spaced about the axis of the sample relative to the thirdradiation source for generating a third output signal indicative of theintensity of radiation impinging thereon.
 23. A device as recited inclaim 18, wherein the second and third channels are angularly spacedapproximately 45° apart and the first and third channels are angularlyspaced approximately 90° apart.
 24. A device as recited in claim 18,further comprising a fourth channel defining a fourth meridional planeextending through the axis and including thereon at least one fourthradiation source mounted adjacent to the sample for emitting a fourthbeam of radiation through the sample, and at least one fourth sensorangularly spaced about the axis of the sample relative to the fourthradiation source for generating a fourth output signal indicative of theintensity of radiation impinging thereon.
 25. A device as recited inclaim 18, wherein the first and fourth channels are angularly spacedapproximately 22.5° apart.
 26. A device as recited in claim 18, whereinthe axis lies within the first meridional plane.
 27. A device as recitedin claim 26, wherein the axis lies within the second meridional plane.28. An instrument for testing characteristics of a material comprising:a translucent cell for receiving a sample of the material; and a housingdefining an aperture for receiving therein the translucent cell, thehousing including: a first light source mounted within the housingadjacent to the aperture for emitting light at a first modulatedfrequency through the translucent cell placed in the aperture; at leastone detector mounted within the housing and spaced angularly relative tothe first light source adjacent to the aperture for converting themodulated light of the first light source into an electrical signalafter the modulated light of the first light source passes through thetranslucent cell, wherein the electrical signal is modulated at thefirst modulated frequency; and a display for converting an output of thefirst detector into a human readable form.
 29. An instrument as recitedin claim 28, further comprising: a second light source for emittinglight at a second modulated frequency through the translucent cell,wherein the at least one detector converts the light of the second lightsource into a second electrical signal at the second frequency after thelight of the second light source passes through the translucent cell,the display converts an output of the detector into a human readableform, and the first and second modulated frequencies are different. 30.An instrument as recited in claim 29, comprising the first and secondlight sources and corresponding detectors fixed along differentchannels.
 31. An instrument as recited in claim 28, wherein the firstlight source is a light emitting diode.
 32. An instrument as recited inclaim 28, further comprising a controller for automatically comparingthe first electrical signal which is indicative of a degree oftransmittance to a database of stored values in order to determine aconcentration of an impurity based on such comparing.
 33. An instrumentas recited in claim 28, wherein the translucent cell includes a capremovably attachable for sealing the sample within the cell.
 34. Aninstrument as recited in claim 28, wherein the translucent cell is aconduit for receiving the material therethrough.
 35. An instrument asrecited in claim 28, further comprising a beam-splitter positioned infront of the light source for directing a portion of the light to areference detector and for indicating an output power of the lightsource to thereby monitor performance of the light source.
 36. Aninstrument as recited in claim 28, further comprising an amplifieroperatively associated with the detector for boosting the electricalsignal.
 37. An instrument as recited in claim 28, further comprising anoscillator operatively associated with the light source for modulatingthe light of the light source at the first modulated frequency.
 38. Aninstrument as recited in claim 28, further comprising a reagentcontained within the translucent cell for mixing with the material andcreating particles which scatter the light.
 39. An instrument as recitedin claim 28, further comprising a reagent contained within thetranslucent cell for mixing with the material and creating fluorescence.40. An instrument as recited in claim 28, further comprising a reagentcontained within the translucent cell for mixing with the material andcreating an optical absorption band which reduces a transmissivity ofthe material.
 41. An instrument as recited in claim 28, furthercomprising a controller operatively coupled to the light source anddetector, and wherein the translucent cell includes an electricalcircuit mounted thereon and operatively associated with the controllerto provide instructions for testing a material.
 42. An instrument asrecited in claim 28, wherein the translucent cell includes a capattachable thereto for sealing the sample within the cell.
 43. A devicefor optically measuring qualities of a substance in ambient lightcomprising: first means defining a sample chamber for receiving thereinthe substance to be measured and defining an axis; second means mountedadjacent to the sample chamber for emitting a modulated beam ofradiation distinguishable from the ambient light based on saidmodulation; third means angularly spaced about the axis of the samplechamber relative to the second means for receiving the modulated beam ofradiation after passage through the sample chamber and substance to bemeasured therein, and for generating a modulated output signalindicative of the intensity of the radiation of the beam impingingthereon; fourth means coupled to the second and third means foractivating the second means and processing the output signal; and fifthmeans for displaying measurement readings based on the output signals.44. An instrument as recited in claim 43, wherein the second means is aradiation source.
 45. An instrument as recited in claim 44, wherein theradiation source is a light emitting diode and an oscillator connectedthereto.
 46. An instrument as recited in claim 43, wherein the thirdmeans is a sensor.
 47. An instrument as recited in claim 43, wherein thefourth means is a microprocessor and memory operatively connected to thesecond and third means.
 48. A method for optically measuring qualitiesof a substance in ambient light comprising the steps of: providing asample chamber defining an axis for receiving therein the substance tobe measured; providing at least two radiation sources mounted adjacentto the sample chamber; emitting modulated beams of radiation from theradiation sources, each source being modulated at a different frequencyand, therefore, distinguishable from the ambient light and each otherbased on said modulation; providing at least one first detectorangularly spacing about the axis of the sample chamber relative to thefirst radiation source; receiving the modulated beam of radiation by thefirst detector after passage through the sample chamber and substance tobe measured therein; generating a modulated output signal indicative ofthe intensity of the radiation of the modulated beam impinging on thefirst detector; activating by a controller the first radiation sourceand the first detector; processing the modulated output signal; andproviding a display for providing measurement readings based on themodulated output signal.
 49. A method according to claim 48, wherein anyangle effects are automatically taken into account by storing a datapoint based upon a calibration with a pure water sample.
 50. A methodaccording to claim 49, further comprising the step of dampening anysignal at the frequency of ambient light.
 51. An instrument fordetermining a concentration of an impurity within a sample, comprising:(a) a housing defining a recess for receiving the sample; (b) a sourceoperatively connected to the housing for emitting optical energy throughthe sample; (c) a detector operatively associated with the housing forreceiving the optical energy and converting the optical energy into adata point for the sample; (d) at least one memory operativelyassociated with the housing, the at least one memory configured forstoring a database of calibration readings for a plurality ofconcentrations of the impurity; and (e) at least one processor incommunication with the at least one memory, wherein the at least oneprocessor is configured for determining the concentration of theimpurity based upon comparing the data point for the sample to thedatabase of calibration readings.
 52. An instrument as recited in claim51, wherein the source is a light emitting diode.
 53. An instrument asrecited in claim 51, wherein the detector is a photovoltaic detector.54. An instrument as recited in claim 51, further comprising: at leastone oscillator within the housing and operatively connected to thesource; a power cell within the housing for driving the at least oneoscillator; and a vial for receiving the sample, the vial defining acenterline axis; a second source operatively connected to the housingfor emitting optical energy through the sample; a second detectoroperatively associated with the housing for receiving optical energy,wherein the light sources and detectors lie on fixed axes and meridionalplanes passing through an axis of the sample.
 55. An instrument asrecited in claim 54, further comprising a base mounted on the vial, thebase having a printed circuit board, wherein the printed circuit boardhas memory for providing data to the processor.
 56. An instrument formeasuring characteristics of a substance comprising: (a) first means fordefining a sample chamber for receiving therein a sample of thesubstance and defining an axis; (b) second means mounted adjacent to thesample chamber for emitting a beam of radiation through the samplechamber and generating an output signal indicative of the intensity ofthe beam of radiation after passage through the sample; (c) third meansoperatively coupled to the second means for storing data including aplurality of reference measurements based upon a plurality of differentreference samples, wherein each reference sample has a differentconcentration of an impurity; and (d) fourth means in communication withthe second and third means, for: (i) receiving a signal from the secondmeans based upon a sample within the first means having an unknownconcentration of an impurity; (ii) comparing the signal to at least aportion of the reference measurements to determine a concentration ofthe impurity in the sample; and (iii) generating an output signalindicative of the concentration.
 57. An instrument as recited in claim56, wherein the first means is a vial.
 58. An instrument as recited inclaim 56, wherein the second means is a light emitting diode and aphotovoltaic detector.
 59. An instrument as recited in claim 56, whereinthe third means is random access memory and read only memory.
 60. Aninstrument as recited in claim 56, wherein the fourth means is amicroprocessor and a software program stored on the third means.
 61. Aninstrument for analyzing color and scattering of an sample, wherein thesample defines an axis, the instrument comprising: first means fordefining a first meridional plane and including thereon second means foremitting a beam of radiation modulated at a frequency, the second meansmounted adjacent to the sample for emitting said beam of radiationthrough the sample, and third means for sensing angularly spaced aboutthe axis of the sample relative to the second means, the third meansgenerating a first output signal indicative of the intensity ofradiation impinging thereon; fourth means for defining a secondmeridional plane and including thereon fifth means for emitting a beamof radiation modulated at a second frequency, the fifth means mountedadjacent to the sample for emitting said beam of radiation through thesample, and sixth means for sensing angularly spaced about the axis ofthe sample relative to the fifth means for generating a second outputsignal indicative of the intensity of radiation impinging thereon; andseventh means for activating the first and fourth means and processingsaid output signals generated thereby.
 62. An instrument as recited inclaim 61, wherein the seventh means activates the second and fifth meanssimultaneously and corresponding signals generated thereby aredistinguishable.